Which of the following shows the polynomial below written in descending order?

3x3 + 9x7 - x + 4x12

A. 3x3 + 4x12 + 9x7 - x

B. 9x7 + 4x12 + 3x3 - x

C. 4x12 + 3x3 - x + 9x7

D. 4x12 + 9x7 + 3x3 - x

To write the polynomial in descending order, arrange the terms from the highest to the lowest degree. Simply base on the exponents of the variable x. You have 3, 12, 1 and 7. In descending order, that would be: 12, 7, 3 and then 1. The answer is D.